Diffusion-weighted imaging as a follow-up modality for evaluation of major salivary gland function in nasopharyngeal carcinoma patients: a preliminary study

The impact of submandibular glands protection on xerostomia as monitored by diffusion-weighted imaging in nasopharyngeal carcinoma patients

PURPOSE

To determine the impact of sparing submandibular glands (SMGs) on alleviating xerostomia and the functional dynamics of the irradiated parotid glands (PGs) and sublingual glands (SLGs) by diffusion-weighted imaging.

METHODS

97 participants underwent 9 rounds of DWI scans before IC (pre-IC), pre-radiation (pre-RT), the midpoint of radiation (mid-RT), the end of radiation (post-RT), 1, 3, 6, 9, 12 (12m-RT) months following radiation. Apparent diffusion coefficient of SMGs (ADCSMG), PGs (ADCPG), and SLGs (ADCSLG), xerostomia questionnaire scores (XQ), and saliva flow rate measures under unstimulated (uSFR) and stimulated condition (sSFR) were documented.

RESULTS

ADCPG, ADCSMG, ADCSLG, and XQ showed a rapid increase with a top at 3m-RT followed by regression, whereas uSFR and sSFR had the reverse trend. The change rate of ADC correlated with the dose to PGs, SMGs, and SLGs, as well as uSFR, sSFR, and XQ scores (p < 0.05 for all, except for uSFR with ADCPG (p = 0.063)). Maingroup for ADCPG, uSFR, and sSFR were significant (p values were 0.028, 0.000, 0.000 respectively); ADCPG in SMG sparing group was lower while uSFR, and sSFR were higher than those in the SMG-unsparing group. Simplegroup for ADCSMG, ADCSLG (all p < 0.05 from mid-RT to 12m-RT), and XQ (all p < 0.001 at mid-, 6m-, 9m-, and 12m-RT) were significant; ADCSMG, ADCSLG, and XQ were lower in the SMG-sparing group.

CONCLUSIONS

SMG protection has a great impact on the functional retention of PGs and SLGs, resulting in alleviating xerostomia and improving quality of life.

TRIAL REGISTRATION

The clinical trial was also registered with the Chinese Clinical Study Registry (registered number: ChiCTR1900024328, Date: July 6, 2019; URL: https://www.chictr.org.cn/showproj.aspx?proj=40726 ).

Multi‑parameter quantitative magnetic resonance imaging in the early assessment of radiation‑induced parotid damage in patients with nasopharyngeal carcinoma following intensity‑modulated radiotherapy

The present study aimed to investigate the value of intravoxel incoherent motion imaging (IVIM) and three-dimensional pulsed continuous arterial spin labeling (ASL) in assessing dynamic changes of the parotid gland in patients with nasopharyngeal carcinoma (NPC) following radiotherapy (RT). A total of 18 patients with NPC who underwent intensity-modulated RT were enrolled in the present study. All patients underwent conventional magnetic resonance imaging, plus IVIM and ASL imaging of the bilateral parotid glands within 2 weeks prior to RT, and 1 week (1W) and 3 months (3M) following RT. Pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (F) and blood flow (BF) were analyzed. D and BF values were significantly increased from pre-RT to 1W post-RT [change rate: Median (IQR), ΔD1W%: 39.28% (38.23%) and ΔBF1W%: 60.84% (54.88%)] and continued to increase from 1W post-RT to 3M post-RT [55.44% (40.56%) and ΔBF%: 120.39% (128.74%)]. In addition, the F value was significantly increased from pre-RT to 1W post-RT, [change rate: Median (IQR), ΔF1W%: 28.13% (44.66%)], and this decreased significantly from 1W post-RT to 3M post-RT. However, no significant differences were observed between pre-RT and 3M post-RT. Results of the present study also demonstrated that the D* value was significantly decreased from pre-RT to 1W post-RT and 3M post-RT [change rate: Median (IQR), ΔD*1w%: -41.86% (51.71%) and ΔD*3M: -29.11% (42.67%)]. No significant difference was observed between the different time intervals post-RT. There was a significant positive correlation between percentage change in ΔBF1W and radiation dose (ρ=0.548, P=0.001). Thus, IVIM-diffusion-weighted imaging and ASL may aid in the detection and prediction of radiation-induced parotid damage in the early stages following RT. They may contribute to further understanding the potential association between damage to the parotid glands and patient-/treatment-related variables, through the assessment of individual microcapillary perfusion and tissue diffusivity.

Imaging of human papilloma virus (HPV) related oropharynx tumour: what we know to date

The tumours of head and neck district are around 3% of all malignancies and squamous cell carcinoma is the most frequent histotype, with rapid increase during the last two decades because of the increment of the infection due to human papilloma virus (HPV). Even if the gold standard for the diagnosis is histological examination, including the detection of viral DNA and transcription products, imaging plays a fundamental role in the detection and staging of HPV + tumours, in order to assess the primary tumour, to establish the extent of disease and for follow-up. The main diagnostic tools are Computed Tomography (CT), Positron Emission Tomography-Computed Tomography (PET-CT) and Magnetic Resonance Imaging (MRI), but also Ultrasound (US) and the use of innovative techniques such as Radiomics have an important role. Aim of our review is to illustrate the main imaging features of HPV + tumours of the oropharynx, in US, CT and MRI imaging. In particular, we will outline the main limitations and strengths of the various imaging techniques, the main uses in the diagnosis, staging and follow-up of disease and the fundamental differential diagnoses of this type of tumour. Finally, we will focus on the innovative technique of texture analysis, which is increasingly gaining importance as a diagnostic tool in aid of the radiologist.

Development and validation of a nomogram for prediction of recovery from moderate-severe xerostomia post-radiotherapy in nasopharyngeal carcinoma patients

PURPOSE

Aim to create and validate a comprehensive nomogram capable of accurately predicting the transition from moderate-severe to normal-mild xerostomia post-radiotherapy (postRT) in patients with nasopharyngeal carcinoma (NPC). Materials and methods We constructed and internally verified a prediction model using a primary cohort comprising 223 patients who were pathologically diagnosed with NPC from February 2016 to December 2019. LASSO regression model was used to identify the clinical factors and relevant variables (the pre-radiotherapy (XQ-preRT) and immediate post-radiotherapy (XQ-postRT) xerostomia questionnaire scores, as well as the mean dose (D_mean) delivered to the parotid gland (PG), submandibular gland (SMG), sublingual gland (SLG), tubarial gland (TG), and oral cavity). Cox proportional hazards regression analysis was performed to develop the prediction model, which was presented as a nomogram. The models' performance with regard to calibration, discrimination, and clinical usefulness was evaluated. The external validation cohort comprised 78 patients. Results Due to better discrimination and calibration in the training cohort, age, gender, XQ-postRT, and D_mean of PG, SMG, and TG were included in the individualized prediction model (C-index of 0.741 (95% CI:0.717 to 0.765). Verification of the nomogram's performance in internal and external validation cohorts revealed good discrimination (C-index of 0.729 (0.692 to 0.766) and 0.736 (0.702 to 0.770), respectively) and calibration. Decision curve analysis revealed that the nomogram was clinically useful. The 12-month and 24-month moderate-severe xerostomia rate was statistically lower in the SMG-spared arm (28.4% (0.230 to 35.2) and 5.2% (0.029 to 0.093), respectively) than that in SMG-unspared arm (56.8% (0.474 to 0.672) and 12.5% (0.070 to 0.223), respectively), with an HR of 1.84 (95%CI: 1.412 to 2.397, p= 0.000). The difference in restricted mean survival time for remaining moderate-severe xerostomia between the two arms at 24 months was 5.757 months (95% CI, 3.863 to 7.651; p=0.000). Conclusion The developed nomogram, incorporating age, gender, XQ-postRT, and D_mean to PG, SMG, and TG, can be used for predicting recovery from moderate-severe xerostomia post-radiotherapy in NPC patients. Sparing SMG is highly important for the patient's recovery.

A review of diffusion-weighted magnetic resonance imaging in head and neck cancer patients for treatment evaluation and prediction of radiation-induced xerostomia

The incidence of head and neck cancers (HNC) is rising worldwide especially with HPV-related oropharynx squamous cell carcinoma. The standard of care for the majority of patients with locally advanced pharyngeal disease is curative-intent radiotherapy (RT) with or without concurrent chemotherapy. RT-related toxicities remain a concern due to the close proximity of critical structures to the tumour, with xerostomia inflicting the most quality-of-life burden. Thus, there is a paradigm shift towards research exploring the use of imaging biomarkers in predicting treatment outcomes. Diffusion-weighted imaging (DWI) is a functional MRI feature of interest, as it quantifies cellular changes through computation of apparent diffusion coefficient (ADC) values. DWI has been used in differentiating HNC lesions from benign tissues, and ADC analyses can be done to evaluate tumour responses to RT. It is also useful in healthy tissues to identify the heterogeneity and physiological changes of salivary glands to better understand the inter-individual differences in xerostomia severity. Additionally, DWI is utilised in irradiated salivary glands to produce ADC changes that correlate to clinical xerostomia. The implementation of DWI into multi-modal imaging can help form prognostic models that identify patients at risk of severe xerostomia, and thus guide timely interventions to mitigate these toxicities.

Application of Diffusion Kurtosis Imaging in Evaluating Acute Xerostomia in Nasopharyngeal Carcinoma Treated With Induction Chemotherapy Plus Concurrent Chemoradiotherapy

Purpose

The aim of this study was to identify the efficacy of diffusion kurtosis imaging (DKI) in tracking and monitoring the dynamic change of parotid glands (PGs), submandibular glands (SMGs), sublingual glands (SLGs), and acute xerostomia in nasopharyngeal carcinoma (NPC) patients treated with induction chemotherapy (IC) plus concurrent chemoradiotherapy (CCRT).

Methods

The prospective study recruited 42 participants treated with IC+CCRT. All patients underwent DKI scanning six times: before IC, before RT, in the middle of the RT course, immediately after RT, and 1 and 3 months post-RT. Mean diffusion coefficient (MD) and mean kurtosis (MK) of PG, SMG, SLG, saliva flow rate measured under resting (uSFR) and stimulated condition (sSFR), and xerostomia questionnaire (XQ) scores were recorded.

Results

At each time point, sSFR was significantly higher than uSFR (p < 0.05 for all). MD of the salivary glands and XQ scores increased over time while MK, uSFR, and sSFR decreased. After IC, the significant differences were detected in MD and MK of bilateral SMG and MK of the left SLG (p < 0.05 for all), but not in MD and MK of PG, uSFR, sSFR, and XQ scores. After RT, sSFR at 1m-RT decreased significantly (p = 0.03) while no significant differences were detected in uSFR and XQ scores. Moderate-strong correlations were detected in ΔMD-PG-R%, ΔMK-PG-R%, ΔMD-PG-L%, ΔMK-PG-L%, ΔMD-SMG-R%, ΔMK-SMG-R%, ΔMD-SMG-L%, ΔMK-SMG-L%, and ΔMD-SLG-R%, with correlation coefficients (p < 0.05 for all) ranging from 0.401 to 0.714. ΔuSFR% was correlated with ΔMD-SMG% (p = 0.01, r = -0.39), ΔMD-SLG% (p < 0.001, r = -0.532), and ΔMK-SMG% (p < 0.001, r = -0.493). ΔsSFR% correlated with ΔMD-PG% (p = 0.001, r = -0.509), ΔMD-SMG% (p = 0.015, r = -0.221), and ΔMK-PG% (p < 0.001, r = 0.524). ΔXQ% was only correlated with ΔMK-PG% (p = 0.004, r = 0.433).

Conclusion

DKI is a promising tool for tracking and monitoring the acute damage of PG, SMG, and SLG induced by IC+CCRT in NPC patients.

The Role of Patient- and Treatment-Related Factors and Early Functional Imaging in Late Radiation-Induced Xerostomia in Oropharyngeal Cancer Patients

Simple Summary

In the present prospective study, we assessed the role of various Magnetic Resonance Imaging biomarkers combined with self-assessed xerostomia questionnaires and patient- and treatment-related factors, in predicting xerostomia at 12 months after chemoradiotherapy for oropharyngeal squamous cell carcinoma. We hypothesized that the integration of pre-treatment imaging biomarkers, which addresses the tissue heterogeneity and individual variations among patients, could improve the accuracy of conventional prediction models that are based only on dose information, ultimately providing a better understanding of the pathophysiological mechanisms underlying radiation induced salivary dysfunction. The implementation of multifactorial models, driven by machine learning algorithms, may improve prediction accuracy of radiation-induced toxicity and tailor individual treatment options for patients.

Abstract

The advent of quantitative imaging in personalized radiotherapy (RT) has offered the opportunity for a better understanding of individual variations in intrinsic radiosensitivity. We aimed to assess the role of magnetic resonance imaging (MRI) biomarkers, patient-related factors, and treatment-related factors in predicting xerostomia 12 months after RT (XER₁₂) in patients affected by oropharyngeal squamous cell carcinoma (OSCC). Patients with locally advanced OSCC underwent diffusion-weighted imaging (DWI) and dynamic-contrast enhanced MRI at baseline; DWI was repeated at the 10th fraction of RT. The Radiation Therapy Oncology Group (RTOG) toxicity scale was used to evaluate salivary gland toxicity. Xerostomia-related questionnaires (XQs) were administered weekly during and after RT. RTOG toxicity ≥ grade 2 at XER₁₂ was considered as endpoint to build prediction models. A Decision Tree classification learner was applied to build the prediction models following a five-fold cross-validation. Of the 89 patients enrolled, 63 were eligible for analysis. Thirty-six (57.1%) and 21 (33.3%) patients developed grade 1 and grade 2 XER₁₂, respectively. Including only baseline variables, the model based on DCE-MRI and V65 (%) (volume of both glands receiving doses ≥ 65 Gy) had a fair accuracy (77%, 95% CI: 66.5–85.4%). The model based on V65 (%) and XQ-Int_mid (integral of acute XQ scores from the start to the middle of RT) reached the best accuracy (81%, 95% CI: 71–88.7%). In conclusion, non-invasive biomarkers from DCE-MRI, in combination with dosimetric variables and self-assessed acute XQ scores during treatment may help predict grade 2 XER₁₂ with a fair to good accuracy.

Diffusion-weighted MRI for predicting treatment response in patients with nasopharyngeal carcinoma: a systematic review and meta-analysis

Early prediction of treatment response in nasopharyngeal carcinoma is clinically relevant for optimizing treatment strategies. This meta-analysis was performed to evaluate whether apparent diffusion coefficient (ADC) from diffusion-weighted imaging (DWI) can predict treatment response of patients with nasopharyngeal carcinoma. A systematic search of PubMed-MEDLINE and Embase was performed to identify relevant original articles until July 22, 2021. We included studies which performed DWI for predicting locoregional treatment response in nasopharyngeal carcinoma treated with neoadjuvant chemotherapy, definitive chemoradiation, or radiation therapy. Hazard ratios were meta-analytically pooled using a random-effects model for the pooled estimates of overall survival, local relapse-free survival, distant metastasis-free survival and their 95% CIs. ADC showed a pooled sensitivity of 87% (95% CI 72–94%) and specificity of 70% (95% CI 56–80%) for predicting treatment response. Significant between-study heterogeneity was observed for both pooled sensitivity (I² = 68.5%) and specificity (I² = 92.2%) (P < 0.01). The pooled hazard ratios of low pretreatment ADC for assessing overall survival, local relapse-free survival, and distant metastasis-free survival were 1.42 (95% CI 1.09–1.85), 2.31 (95% CI 1.42–3.74), and 1.35 (95% CI 1.05–1.74), respectively. In patients with nasopharyngeal carcinoma, pretreatment ADC demonstrated good predictive performance for treatment response.

Feasibility of DW-MRI analysis of salivary glands during head and neck radiotherapy

INTRODUCTION

With no effective treatment for xerostomia, there remains an unmet need to reduce radiation induced toxicity. Measuring physiological changes during RT in salivary glands using DW-MRI may predict which patients are most at risk of severe toxicity. This study evaluated the feasibility of measuring apparent diffusion coefficient (ADC) in the major salivary glands and describes the observed changes in volume and ADC during RT.

METHODS

Scans were acquired at baseline (MR_base) and after 10 fractions (MR_rpt). Sequences included T1 post contrast fat saturated (T1PCFS) and DW-MRI (5b values, 0-1000 s/mm2). Ipsilateral and contralateral parotid (iPG/cPG), submandibular (iSMG/cSMG) and sublingual glands (iSLG/cSLG) were delineated on T1PCFS, modified on b0 and copied to the ADC map.

RESULTS

31 patients with intermediate/high risk squamous cell carcinoma (SCC) of the oropharynx were evaluated. On 124 scans, SMG and SLG delineations were successful on all; parotids were fully contoured in 90.7%. Baseline mean ADC were significantly different between each gland type (p < 0.0001). IPG and cPG volume decreased during treatment by 6.7% and 11.2%. ISMG, cSMG, iSLG and cSLG volume increased by 6.9, 0.9, 60.8 and 60.3% respectively. All structures showed an increase in mean_ADC values. For each gland the increase in ADC was statistically significant p < 0.0001. A smaller mean percentage increase in ADC was observed in the group experiencing a higher grade (2 or > ) of toxicity.

CONCLUSION

It is feasible to measure volume and ADC of the salivary glands prior to and during RT for HNC. Early data suggests a lower rise in ADC during treatment is associated with more severe late xerostomia.

Dynamic Three-Dimensional ADC Changes of Parotid Glands During Radiotherapy Predict the Salivary Secretary Function in Patients With Head and Neck Squamous Carcinoma

Objective

To investigate the changes of three-dimensional apparent diffusion coefficient (3D-ADC) of bilateral parotid glands during radiotherapy for head and neck squamous cell carcinoma (HNSCC) patients and explore the correlations with the radiation dose, volume reduction of parotid gland and the salivary secretary function.

Materials and Methods

60 HNSCC were retrospectively collected in Sichuan cancer hospital. The patients were all received diffusion-weighted imaging (DWI) scan at pre-radiation, the 15^th radiation, the 25^th radiation and completion of radiation. Dynamic 3D-ADC were measured in different lobes of parotid glands (P1: deep lobe of ipsilateral; P2: superficial lobe of ipsilateral; P3: deep lobe of contralateral; P4: superficial lobe of contralateral), and the 3D-ADC of spinal cord were also recorded. Chewing stimulates test, radionuclide scan and RTOG criteria were recorded to evaluate the salivary secretary function. Pearson analysis was used to assess the correlation between 3D-ADC value, radiation dose, volume change, and salivary secretary function.

Results

The mean 3D-ADC of parotid glands increased. It began to change at the 15^th radiation and the mostly increased in P1. However, there was no change for the maximum and minimum 3D-ADC. The 3D-ADC values of spinal cord changes were almost invisible (ratio ≤ 0.03 ± 0.01). The mean 3D-ADC was negatively correlated with the salivary secretary function (r=-0.72) and volume reduction of different lobes of parotid glands (r1=-0.64; r2=-0.61; r3=-0.57; r4=-0.49), but it was positively correlated with the delivered dose (r1 = 0.73; r2 = 0.69; r3 = 0.65; r4 = 0.78).

Conclusion

Dynamic 3D-ADC changes might be a new and early indicator to predict and evaluate the secretary function of parotid glands during radiotherapy.

Diffusion weighted imaging in submandibular gland sparing helical tomotherapy for nasopharyngeal carcinoma

PURPOSE

To verify clinical significance of submandibular gland (SMG)-sparing during helical tomotherapy (HT) for nasopharyngeal carcinoma (NPC) from the perspective of imaging by using diffusion weighted imaging (DWI).

MATERIALS AND METHODS

In this prospective study, 60 NPC patients scheduled for radical SMG-sparing HT were enrolled. All patients underwent DWI examinations prior to HT (pre-HT) and 1, 3, 6, 9, 12 months post HT. Mean apparent diffusion coefficient (ADC) values of bilateral parotid glands (PGs) and submandibular glands (SMGs) were measured. Differences of ADC and changes of ADC pre and pro HT (ΔADC) among SMG-spared, SMG-unspared and PGs were compared and the associations betweenΔADC and variations of patient-rated xerostomia questionnaire summary scores (XQ-sum) were further tested.

RESULTS

ADC_post-HT and ΔADC_post-HT of SMG-spared were both much lower than of SMG-unspared and a strong dose-response relationship was detected between mean radiation dose and ΔADC of SMGs. Dynamic change trends of PGs, SMG-spared and SMG-unspared were similar, with initial increase at 1 m-post-HT followed by little change at 3 m-post-HT and then gradual decrease over time. But for SMG-unspared, there was no obvious change of ADC from 6 m-post-HT to 12 m-post-HT. The dynamic change trend of XQ-sum was nearly in line with that of ADC on the whole. And a positive correlation between mean ΔADC_1m-post-HT of bilateral SMGs and variation of XQ-sum_1m-post-HT in patients with bSMG-unspared were found (r = 0.693, P < 0.001). Multivariate stepwise regression analysis showed that whether spared SMG or not was the only independent predictor correlated to XQ-sum_post-HT at each follow-up timepoint.

CONCLUSION

SMG-sparing technique could significantly improve subjective xerostomia post HT in NPC patients from the perspective of imaging.